Vibration regulator



June 24, 1930. w. BocK ET AL VIBRATION REGULATOR Filed March 3, 1928 2 Sheets-Sheet l 1 EL @lr e 12 a2 @LI @LT JT INVE TORS wmmwg k KM June 24, 1930. w, oc ET AL 1,767,236

' VIBRATION REGULATOR I Filed March 5, 1928 2 Sheets-Sheet 2 as J L sz L11; I a! at? m Va IHVE T0 WM KM BY 1 Odd? HT OHHEY Patented June 24, 1930 UNITED STATES- WAL'IHER BOOK, OF BERLIN-SCHONEBERG, GERMANY, AND KARL BATH, OF NEW YORK, N. Y., ASSIGNORS To 'C. LORENZ-AKTIENGESELLSCHAFT, F BERLIN- TEMPELHOF, GERMANY VIBRATION Application filed March 3, '1928, Serial No.

i This application relates to an electrical regulator operating according to fast regulating or Tirrill principle. The mam ob ect of the invention is to replace the mechanical arrangement for controlling the vibrations and the regulating influence by a more accurate and precise electric control of sald vibrations.

Another object of this invention 18 to v make the closing and opening of regulating influence by purely electrical forces, and not by mechanical means.

Another object is to have an electrlcal relay for applying and withdrawing the regulating action, thereby increaslng the speed and accuracy of regulation.

A further'object is to introduce vacuum tube control for a relay to secure agreater sensitivity of response of the vibration regu- 2 lator to variations in the magnitude to be regulated.

The invention is further described with reference to the accompanying drawings, which illustrate as follows: 5 Fig. l is a dia rammatic representation of the operation 0 vibration regulator with reference to the duration of time periods of regulating influence;

Fig. 2 is a diagram of connections suitable for carrying out the object of our invention, .for the purpose of controlling the foutput voltageof a generator;

Fig. 3 is a similar arrangement to keep the frequency of an alternating current gen-- erator constant;

Fig. 4 is a diagrammatic representation of the variation in time intervals for a modified regulating scheme;

REGULATOR 261,095, and in Germany March 14, 1927.

frequency of an alternating current generator.

The invention will be described with a short reference to the present art of regulation. Referring to the regulation of electrical current, for instance, the excita-' after a change has occurred in the magni 4 tude to be influenced, and regulated (that is, in this case, of the current). This regulating mechanism exercises only then a corresponding regulating influence 1 so that meanwhile the magnitude to be regulated may already have passed through a further change and in that Way the regulating influence lags behind the change, hence the name, slow regulation. Such a regulation even when used as rough, in connection with more definite regulation, can only apply to small and slow changes of the magnitude to be held constant, and fails entirely when it is a case of extreme precision, as for instance, for speed regulation of electrical machines for generation of high frequency current or for securing synchronousoperation of several devices, or else when it is a question ofgenerating extremely constant voltages such as for measuring purposes.

For such uses the only method that need be practically considered is the other already well-known art of regulation to which this present invention also refers, and which therefore may be called fast regulation, or

regulation accordingto the Tirrill principle. This method is already utilized for regulation of voltages by the well-known Tirrill voltage regulator for electric generators, and lately also for keeping constant the speed of the machine by the so-called Schmidts centrifugal contact regulator. The principle of this regulating method consists in the fact that the permanent, that is also the normal condition, such as the constant (pressure or speed) has a regulating influence periodically applied to and A withdrawn from it, so that even with the least change of the magnitude to bekept constant the regulating action is fully exercis'ed and the regulating force is thereby released immediately without any noticeable delay.

There 1s a further distinction of such a regulating method as againstthe above mentioned slow'regulation'in which the main disadvanta among other disadvantages, is the equalization phenomena following the changes incurrent. This distinction is that such equalization henomenadisturbing the regulating procedure are practically excluded, especially the influence of-the inductance of the windings such as exciting windings. This is made possible by using the so-called over regulatlon, that is, that the regulating influence is made several times bigger than is necessary for producingthe normal condition. At the same time this excessive regulating force cannot exercise its full action, since it is forcibly applied and withdrawn right at the beginning of its'regulating action. By this means the advantage is secured that the delay phenomena are practically entirely excluded, and an instantaneous regulating influence I is obtained.

The re uired forced periodic application and with rawal of regulation have in the present-day arrangements been secured'in a mechanical manner, such as by spring contact means. This is, for instance the case in'the above referred to. Tirrill voltage regulator, in which a movable-contact arm carrying a contact is. closing and opening periodically with a corresponding fixed contact to apply and withdraw the regulating influence. Also, in the speed regulator above referred to, a swinging device car contacts is used in-conjunction wit a suitable opposite contact, for' maintaining the but onl ng the manner, the relation of the regulating duration to the regulating suspension duration ing duration of a relay. correct value of the magnitude to be' kept I description 0 individual details. Similar. v

notations in the drawingsrefer to similarv elements.

As an example, in a machine the ressure of which must be kept constant or t 'e speed of which must be equal to or synchronous with another machine, there may be included a resistance in the exciting winding and a suitable voltage applied said exciting winding (for 1nstance, from a separate source of excitation, 'or with self-excited machines from the armature terminals)? When the circuit is closed a current will increase according to curve a in the accompanyi Fig. 1, that is, its final value will be reac ed only after a certain time, which a is determined by the time constant of the circuit.- If a value dependent on the ex-,

citing current, such as terminal ressure the exciting current, then it is well known that the regulating action will not occur immediately at its full value on account of the slowness of the increase in current, after a la se of a definite time.

or speed is to be changed by in uencing f Especia ly when it is a" question of regulatmg large machines with considerable-1nductanoe of its magnetizing winding, this delay may have relatively large value. We have to deal in this case therefore, with the so-called slow regulation. If however, a suitably chosen resistance is. included in the circult after a short period of time t.,

for instance, by opening the contacts of a shuntcircu'it, then the current would increase ,to a point A and would decrease accordin to curve 6, which is represented as an in erse of curve 'a. In this wa a point B is reached in a short period 0 time t.,. At this instant the resistance is again short circuited by closing of the contacts, that is,

'it is excluded 'so that the current will inspeed. Inthis case both contacts are forced to close and open at a rate determined by trical forces rather than by mechanical.

The invention therefore consists, briefly, of a device in which a regulating current or volta e derived from the arrangement to be re ated determines, in an electrical uence 'by elec-' crease 'a ain to point C, to be again reduced by a su With a definite relation between. the o and closing of the contacts, that is, t e application andwithdrawal of re lating resistance, the current will reac disappears entirely since it .is a plied only indirectly to the armature and t rough this a ain to the terminal potential or the s d.

p to the time interval which in the rawing is indicated as t it is assumed that the an intermediate value represented by the curve (1.

' uent inclusion of the resistance.

mng

intervals of closing of contacts i are,

' later the relation of it to t is further resmaller than the intervals of opening the contacts 255., It now this relation of opening and closing intervals of the contacts and respectively of the application and withdrawal intervals of the regulating resistance are changed, in such a way, for instance, that If, is larger and t, is smaller, then the average current cl is automatically increased to a higher average value. If

duced, as after the instant '03, as illustrated in the drawing, the current again drops.

As can be seen, these changes in the average current take place very rapidly, that is, after one or two openings or closings of contact, and this depends, as can be readily'seen, on the shape of the curves at and b,

that is, on the proper dimensioning of the regulating resistance. In the drawing the opening and closing intervals, respectively t and t are illustrated for the purpose of survey for the same regulating period 12. It represents therefore in this case a fast regulator which would operate on a vibration principle, and which is thefmore accurate the more often the change from opening to closing takes place during a unit time.

Fig. 2 shows a switching arrangement ac-' cording 'to the invention, in which forced periodic opening and closing of regulating resistance takes place ,by means of a relay while the relation of opening and closing intervals which determine the degree of regulating action is controlled in a purely electrical manner by periodic charging and discharging of a condenser. The value of this relation is determined by the magnitude to be held constant. Fig. 2 applies specifically to a voltage regulator. Item 1 represents a dynamo machine which for simplicity is represented as a direct current machinei with separate excitation. Item 2 is the magnet winding,-3 is the regulating resistance, and4 is a separate source of energy for securing the constant exciting field. The machine supplies the network 5. A regulating resistance 6 is connected in the exciting circuit of the machine and is switched in and out periodically by, means of a relay 7, in such a way that there is an average exciting current corresponding to the relation of opening and closing intervals of the relay 7, as described in connection with Fig. "1. By this means there is secured quite a definite terminal potential on the machine 1. According to this invention the control of opening and closlng intervals of follows Inthe grid circuit (5f a tubeB there a condenser 16 together with a suitable source of biasing-potential 9. This condenser is connected atone terminal to the resistance relay 7 takes place.as

10 which .lies across the network potential and is thereby charged to a potential dependent on the terminal potential of machine l-which is to be held constant. Since the internal resistance of a tube depends on the potential applied to its rid, the resistance of the tube 8 is quite 1. Thus, if the value of the terminal potential is changed, the grid potential is also changed and thereby also the internal tube resistance, the latter is reduced with the rise of grid potential, and rises with the fall of the grid potential. Thischanging of the internal tuberesistance determines the charging and discharging intervals of condenser 11. This latter is connected to the grid of asecond tube 13 in connection with a biasing potential 12'. The biasing potential 12 is chosen in such a way that it counteracts the pogential 14 representing the source of ano e current. The series resistance 14 serves to set the charging inter-. val to a definite value. p

Assume now that the contacts 15 of the relay 7 are closed. The condenser 11 is then chargedby the battery 14; this eventually makes the potential on the grid of the tube so highly positive that an anode current begips to flow. If this is big enough the relay efinitely determined by the terminal potential of machine 7 1s actuated and opens the contact 15, since its Windinglies in the anode clrcint of the tial of machine 1 to be 'keptyconstant, and

their relation is' correspondin'gly changed. If for instance the ,potenti'al'is high, then the resistance of tube 18 is low, therefore the charging of the condenser 11 at the closing of the contact 15 takes place slowly, and dischargingtakes place rapidly, whereby the duration ofsthe closing of contacts 1s relatively long and the duration of the o en- 'ing of the contacts is relatively short. the. other hand the I grid potential is low (that is, a-trmi nal potential of the machine is reduced) theri' the-resistance of the tube is higher, the charging takes place relatively faster, the discharging takes place relatively slower;- in other words, .the duration of closing of contact 15 is shorter and the duration of opening correspondingly longer... The movement carried out by con tact 15 is 'similarly carried out by. a contact I 17 controlled by the same relay 7. This contact in its turn controls the regulating resistance 6 of the exciting c1rcu1t of the ma- I chine 1 with a similar relation of closing and opening. In the last example, where the ma inc potential was reduced, it resulted in shortening. of the closing duration and a.

corresponding lengthening of the opening duration of the] contact 15, and therefore also the increase of the closing duration and respective shortening of the opening duration of contact 17 This would be equivalent, as a glance at Fig. 1 would show, to

A an increase in the average exciting current (1 in the exciting circuit of the machine, as it is shown, for instance, in Fig. 1 after the instant marked t The practlcally instabtaneous increase in the average value d of the exciting current offthe machine without delay or slowness results in a similar increase of the terminal potential so that the original potential is thereby maintained.

Fig. 3 shows an analogous arrangement ,using the above described switching arrangement for regulation of the speed or for syn chronizing of rotating machines or devices.

As an example, Fig. 3 refers to keeping ac- 1 curately constant the speed of a h1gh frealternating source to as constant a value as possible. The driving motor is fed from direct current network 21. Its exciting winding is indicated by 22. Item 23 represents an adjusting resistance in the exciting circuit, and 24 is a regulating resistance corresponding to resistance 6 of The regulation takes place in such a way I that the alternating current of machine frequency v and the alternating current from a constant fixed standard frequenc v, are applied to coils 25 and 26 of a di erential transformer. The secondary coil 27 of this.

transformer will thenhave a resulting current which depends on the relative phase difference of the two currents. This is rectified by means of a two-way double tube .rectifying arrangement consisting of valve tubes 28 and 29 and is utilized from the terminals of a resistance 30. The potential of resistance -30 is therefore dependent on the resulting current in coil 27 which in its turn, as described above, depends on the relative phase shift of the two currents of frequencies v andv Since v, is standard and is supplied constant, this potential depends on the deviation of frequency v,,,, that is, the change in the speed of the high frequency machine 18, and respectively driving machine 20.

The potential existing on resistance 30 and corresponding to the definite speed op: e'rates now in exactly the same manner as was the case in Fig. 2, on an arrangement for controlling a relay which opens and closes the regulating resistance24 on the driving machine -20. The arrangement consists again of the two tubes 8 and 13, the re lay 7 with contacts 15 and 17, grid condenser 16 and 'controllin condenser 11. Numeral 9 is again the gri biasing battery of the tube 8, and 12 the same for tube 13, while 14 is the anode current source and 14 ad'usting resistances.

f the machine runs the least amount too fast, that is, if the machine frequency v,., is by-the least amount larger,than the average superimposed current in the secondary coil 27 would produce in the resistance 30 such a change in potential" that with the correct setting of the normal hase difference of the two currents of requency v and v, as well as with the correct relative activation of contacts 15 and 17 ofrelay 7,, theresultin current in the motor excltmg circuit would immediately assume a new value which would bring back the origmal speed. In the example illustrated, that 1s, Where the speed mayhaveincreased, the average exciting current is increased so that the tendency to increase all speed 1s suppressed at its inception. If it is necessary to regulate the speed absolutely constant, as in the present example, then the controlling frequenc stant. For t is urpose any suitable current source may be used, such as a piezoelectric crystal oscillator, a small encased tube sender, or even the amplified current of a usual pendulum oscillator, etc. If it is a case of synchronizing two rotating arrangements, for instance, of two rotatm machines, then it should not be understoor that v, is a locally roduced standard controlling frequency, Eut that it 1s an alternating current frequenc derived fromthe synchronizing device whlch is sent by means of wires or without wires to the arrangement to be synchronized that is, as m the case according -to Fig. 3, to the machme 20.

v. must be practically con- The latter alternatmg current frequency from the sending or synchronizing side may be produced as an example by applying a small alternating current generator on the shaft of the synchronizing arrangement. A similar alternating currentgenerator is then mounted on the shaft of the device to be synchronized, that is, in the case of F1 3 on the shaft of machine20 (corres on ing to high frequency machine 18 of ig. 3). If the frequency of the two alternating currents are exactly alike at the synchronism of the two dev1ces (one frequency of the current from the synchronizing arrangement, the other from-the arrangementto be synchronized), and if the correct relative phase difference is present at synchronism, then the least deviation of the arrangement to be synchronized from the synchronous condition and the resulting phase difference would influence the speed instantaneously in accordance with the manner described in Fig. 3, in such a way that a continuous syn.- chronism is maintained.

A further example of carrying out the idea of the invention is represented in Figs. 4 to 6. The periodic opening and closing of the regulating relays is secured by means of an alternating current of suitable frequency, while the duration of openingand closing within a regulating period onwhich the amount of regulation depends is secured by a variable biasing potential of the relay which depends on the magnitude to be regulated, such as the terminal potential or speed.-

Fig. 4 represents diagrammatically the corresponding time relations. In this figure, 4 has for an abscissa the time and for the ordinate the force. The linela parallel to the abscissa axis is the force which is necessary to cause the touching of the two re- 'the: relay a constant force (constant biasing potential 6) as well as a periodical, preferably sinusoidal changing force :20, which is superimposed on the first so that it re- 7 sults in the total active force 0.

The interval of closing of the contacts .9 and the interval of opening 0 during one'period p of regulation would then be represented as in the figure. If, as in Fig. 4 the constant force 6 is changed, that is, the biasing of the relay, then it can be readily seen that the closing interval 8 has increased relative to the opening interval 0 during one regulation period so that with this arrangement also the same effect is secured as that in Figs. 2 and 3, i. e., the changing of the magnitude to be influenced acts on the relation of the intervals of a relay' mediate resistance 3. Item 6 represents again a regulating resistance inserted periodically 1n the clrcu'lt of exciting wlnding.

' A relay 31 carries two windings, 32 and 33,

and is periodically excited by means of a suitable h alternating potential source 34 which supplies the winding 32, and which would correspond to'curve m of Fig. The

second winding 33 which may bev designated.

as a polarizing winding, is connected to a potential difference dependent on the potential of machined to be held constant. This latter is obtained by.means of a potentiometer 10 across the terminals of the network. Iffor instance the machine potential is increasing, then the potential of potentiometer 10 is correspondingly increased, and therefore the constant premagnetization of relay 31. This results in the increase of. the constant force acting on the armature of the relay, which results in an increase of closing interval in relation to opening interval as illustrated in Fig. 4". This latterfinally causes, as can be readily noticed, an increase of the opening interval of the resistance 6 in relation to the closing interval during a regulation period and this again results, as a glance at Fig. 1 after the time period t would show, in the fact that the average exciting current d is. decreased and thereby also the terminal potential of the machine 1, that is, the latter will be maintained at a. constant value. Fig. 6 shows a corresponding arrangement for speed regulation as a counterpart of Fig. 3. Item 18 represents again a high frequency machine, the exciting winding of which is omitted for the sake of clearness. Item 20 is the driving machine which in this example is a direct current shunt motor with magnetizing winding 22 and a regulating resistance 24 for periodic control. Item 21 is the direct current network supplying the motor, and item 19 is the utilizing network of the high frequency machine; v represents again,

as in Fig. 3, the frequencyof the arrangement to be regulated, in this case the frequency derived from the machine, that is here the machine frequency itself; V is the controlling or synchronizing frequency necessary for controlpurposes, exactly as in thearrangement according to Fig. 3. Items 25 and 26 are the input coils, and 27 is the secondary coil of a differential transformer. Items 28 and 29 are two rectifier tubesyand item 30 is a resistance, from the ends of which is obtained a potential corresponding to the speed or frequency to be regulated.

Item 31 is the control relay with a winding 32 which is again supplied by a constant alternating current froma sour'ce 34 with a resulting periodical magnetizing field, while item 33 is a biasing coil connected to the terminals of resistance 30 to produce the magnetic force of a constant direction. The relay contacts 36 are again connected to the ends of the regulating control resistance 24. As the relay arrangement may be fixed, while the resistance may be rotating with the rest of the field structure, slip-rings 35 are supplied between the two. The arrangement of contacts 36 on one' or the other w lags behind the controlling or synchronizing current, say by 90 phase difference, than an increase in the machine speed or an in-, crease in frequency would result in an increase of current in the coil 27, This means an increase in the potential ofthe resistance 30 and therefore anincrease in the premagnetization of relay 31, which would again result in an increaseof closing interval relative to the opening interval.

Asa glance at Fig. 1, after the instant t would show, thisis equivalent to an increase in the resulting average current flowing through the field windings, causing the speed to be held back to its former value.

In the claims the expression response current shall be understood to mean the current required to cause .the touching of the relay contacts, so that for all currents which are greater than the response current the contacts are closed and for all currents which are smaller than the response current the contacts are open.

Having describedmy invention, what ,I believe-to be new and desire to secure and protect by Letters Patent \of the United States -is-:-

1; In a speed regulating system for a rotatable body, an electric circuit for controll ing the speed of said body, a relay, a source of alternating current of constant frequency and amplitude for periodically energizing and deenergizingsaid relay, means for der vlng an electric voltage proportional to the speed ofsaid rotatable body, a biasing circuit for said relay supplied by said voltage, the current flowing in said biasing circuit being approximately e ual to the response current of said rela'y hen the speed of said rotatable body is, normal and circuit connections whereby said relay controls said first-mentioned circuit.

2. In a speed regulating system for an electric motor, a speed influencing circuit for said motor, a relay, a source of alternating current of constant frequency and amplitude for periodically energizing and deenergizing said relay, means 'for deriv- 1ng an electric voltage proportional to the speed of, said motor, a biasing circuit for said relay supplied by said voltage, the current in said biasing circuit being approximately equal to the response current-of said relay when the said motor is operating at normal speed, and circuit connectlons where ing circuit.

3. A speed regulating system for an electric motor, a shunt circuit for said motor, a dynamo driven by said motor, a relay, a source of alternating current of constant frequency and amplitude for periodically energizing and deenergizing said relay, a biasing circuit" forsaid relay supplied from said dynamo, the current in said biasing circuitbeing approximately equal to the response current of said relay when the speed of said motor is normal, and circuit connecby said relay controls said speed influenctions whereby said relay controls said shunt circuit. 1 v

4. In a speed'regulating system, a means the conditionof which is to beregulated,

an electromagnetic means for regulating said condition, said electromagnetic means being periodically operated by an alternating current of onstant frequency and amplitude and adapted to periodcally influence the conditions to beregulated, means for deriving an electric voltage proportional to 'thec'magnitnde of the condition to be regulated, a biasing circuit for said electromagnetic means supplied by said voltage,

the current in said biasing circuit being ap proximately equal to'the response current of-said electromagnetic means when the condition to be regulated is normal.

5. In a speed regulating system, a prime mover, means for generatlng an alternating current of a frequency corresponding to the speed of said prime mover, a source of alternating current of constant frequency and amplitude, means for superimposing one of said alternating currents on the other, means for producing a direct current of varying intensity correspondin ,to relative phase changes of both of said currents, a speed regulating circuit for said prime mover, a relay regulating device adapted to control said speed regulating circuit by periodically imposing on and withdrawing a regulating force from said circuit, a second source of alternating current of constant frequency and amplitude for operating said relay periodically and means to bias said relay by said direct current, said biasing current in current of said relay.

a state of normal speed of said prime mover being,approximately equal to the response 6. In a speed regulating system, a direct I current motor, 'a high frequency generator driven by said motor, awsource of alternating current of constant frequency and amplitude, equal to thefrequency and amplitude of the current derived from said generator at normal speed, means for su rimposing one of said currents on the ot er,

.means for deriving a direct current vary ing in accordance with the relative phase difference between said alternating currents, a shunt circuit for said'motor, a resistance in said shunt circuit, a relay for periodically short circultmg said resistance, a second source of alternatlng current of constant frequency and amplitude for operating said relay and means for biasing said relay by said direct current, said biasing current being approximately equal to the response current of said relay when the motor is operating at normal speed.

In testimony whereof we have afiixed our signatures.

WALTHER BOOK. KARL BATH. 

